Solutions and catalysts comprising group VI metal, group VIII metal, phosphorus and an additive

ABSTRACT

This invention provides a catalyst formed by bringing together, in an aqueous medium, at least one phosphorus compound, at least one Group VI metal compound, at least one Group VIII metal compound, and an additive which is
         a) tetraethylene glycol,   b) polyethylene glycol having an average molecular weight in the range of about 200 to about 400,   c) a mixture of tetraethylene glycol and polyethylene glycol having an average molecular weight in the range of about 200 to about 400, or   d) a mixture of (1) tetraethylene glycol and/or polyethylene glycol having an average molecular weight in the range of about 200 to about 400 and (2) one or more of monoethylene glycol, diethylene glycol, and triethylene glycol,   forming an impregnated carrier; and
 
drying the impregnated carrier. The molar ratio of additive to the total moles of Group VI metal and Group VIII metal is about 0.36:1 to about 0.6:1.

REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 13/391,336,now U.S. Pat. No. 9,254,478, issued on Feb. 9, 2016, which is theNational Stage of International Patent Appl. No. PCT/EP2010/062282 filedon Aug. 24, 2010, which in turn claims the benefit of U.S. ProvisionalPatent Appl. No. 61/236,436, filed on Aug. 24, 2009, the disclosures ofwhich are incorporated herein by reference.

TECHNICAL FIELD

This invention relates to concentrated solutions comprising a Group VImetal, a Group VIII metal, and phosphorus, and to catalysts made fromsuch solutions.

BACKGROUND

A variety of catalysts for hydrotreating, hydrodesulfurization, and/orhydrodenitrogenation are known in the prior art and/or are commerciallyavailable. In this connection, EP 0601722 describes catalysts forhydrodesulfurization and hydrodenitrogenation of hydrocarbon oils. Thecatalysts therein are formed by impregnation of an alumina carrier; theimpregnation solution contains at least one Group VI metal element, atleast one Group VIII metal element, phosphoric acid, and an additiveagent. In the impregnation solutions of EP 0601722, the additive agentsinclude at least one dihydric or trihydric alcohol having 2 to 10 carbonatoms per molecule, and ethers of these alcohols; the amount of additiveagent is such that the molar ratio of additive agent to total moles ofthe Group VI metal element and the Group VIII metal element is in theorder of 0.05:1 to 3:1. However, during preparation of solutionsaccording to EP 0601722, it was observed that a solution containingpolyethylene glycol-200 at an additive:metal ratio of 0.22:1, aphosphorus to Group VI metal ratio of 0.60:1, and a molybdenumconcentration of about 450 g/L (expressed as MoO₃) containedprecipitate. In contrast, for a solution in which the polyethyleneglycol-200 was at an additive:metal ratio of 0.22:1, the phosphorus toGroup VI metal ratio was 0.14:1, and the molybdenum concentration wasabout 450 g/L (expressed as MoO₃), no precipitate was seen.

When forming catalysts for hydrotreating, hydrodesulfurization, and/orhydrodenitrogenation via impregnation of a support, precipitateformation in the impregnation solution is usually undesirable. Thus, theart continually strives to form impregnation solutions withoutprecipitate from which to make catalysts with higher activities forhydrotreating, hydrodesulfurization, and/or hydrodenitrogenation.

SUMMARY OF THE INVENTION

This invention provides solutions comprising Group VI metal, Group VIIImetal, and phosphorus, which solutions have higher concentrations of aparticular additive, and permits precipitate-free solutions havinghigher concentrations of phosphorus than previously achieved, whilestill having the properties of an impregnation solution (e.g., thesolution can sufficiently impregnate the support, and the catalystcomponents do not adhere to the impregnation solution's container). Alsoprovided by this invention are processes for forming such solutions, andcatalysts made from such solutions.

An embodiment of this invention is a process for forming a solutioncomposition, which process comprises forming a primary solution bybringing together, in an aqueous medium,

i) at least one phosphorus compound,

ii) at least one Group VI metal compound,

iii) at least one Group VIII metal compound, and

iv) an additive which is

-   -   a) tetraethylene glycol,    -   b) polyethylene glycol having an average molecular weight in the        range of about 200 to about 400,    -   c) a mixture of tetraethylene glycol and polyethylene glycol        having an average molecular weight in the range of about 200 to        about 400, or    -   d) a mixture of (1) tetraethylene glycol and/or polyethylene        glycol having an average molecular weight in the range of about        200 to about 400 and (2) one or more of monoethylene glycol,        diethylene glycol, and triethylene glycol.        The molar ratio of additive to the total moles of Group VI metal        and Group VIII metal is above 0.30:1, and the atomic ratio of        phosphorus to Group VI metal is at least about 0.33:1.        Optionally, the primary solution is heated at a temperature        above about 40° C. to form a heated solution. The heated        solution is optionally cooled to form a cooled solution.

Another embodiment of this invention is a solution composition formed bythe just-described process. Still another embodiment of this inventionis a process for forming a catalyst, which process comprises bringingtogether a carrier and an impregnation solution comprising a compositionof this invention.

These and other embodiments and features of this invention will be stillfurther apparent from the ensuing description and appended claims.

FURTHER DETAILED DESCRIPTION OF THE INVENTION

As used throughout this document, the phrases “solution composition” and“solution composition of this invention” refer to the compositionsdescribed herein as solutions comprising a Group VI metal, a Group VIIImetal, phosphorus, and the additive, where the molar ratio of theadditive to the total moles of Group VI metal and Group VIII metal isabove 0.30:1. The phosphorus and Group VI metal are typically in atomicratio of at least about 0.33:1, and the Group VI metal and the GroupVIII metal are generally in an atomic ratio of at least about 1.5:1.

Throughout this document, the phrases “hydrogenation metal” and“hydrogenation metals” refer to the Group VI metal or metals and theGroup VIII metal or metals collectively. As used throughout thisdocument, the term “Group VI metal” refers to the metals of Group VIB.

As used throughout this document, the phrases “as the Group VI metaltrioxide,” “reported as the Group VI metal trioxide,” “calculated as theGroup VI metal trioxide,” and analogous phrases for the Group VI metalsas their monoxides and phosphorus as phosphorus pentoxide (P₂O₅) referto the amount or concentration of Group VI metal, Group VIII metal, orphosphorus, where the numerical value is for the respective oxide,unless otherwise noted. For example, nickel carbonate may be used, butthe concentration of nickel in the solution is stated as the value fornickel oxide.

Throughout this document, unless otherwise noted, the term “theadditive” refers to a) tetraethylene glycol, b) polyethylene glycolhaving an average molecular weight in the range of about 200 to about400, c) a mixture of tetraethylene glycol and polyethylene glycol havingan average molecular weight in the range of about 200 to about 400, ord) a mixture of (1) tetraethylene glycol and/or polyethylene glycolhaving an average molecular weight in the range of about 200 to about400 and (2) one or more of monoethylene glycol, diethylene glycol, andtriethylene glycol. Polyethylene glycols are usually referred to bytheir average molecular weight; for example, polyethylene glycol 200 hasan average molecular weight of about 200. Preferred polyethylene glycolsare those having an average molecular weight between about 200 and about400; more preferred is polyethylene glycol having an average molecularweight of about 200. Preferred additives include polyethylene glycol200, and mixtures of triethylene glycol with tetraethylene glycol and/orpolyethylene glycol having an average molecular weight in the range ofabout 200 to about 400.

When the additive is a mixture of (1) tetraethylene glycol and/orpolyethylene glycol having an average molecular weight in the range ofabout 200 to about 400 and (2) one or more of monoethylene glycol,diethylene glycol, and triethylene glycol, the component glycols aregenerally in proportions such that a solution that does not have aprecipitate either initially, or after heating and/or cooling. Anotherconsideration for the mixtures is that for additives with higher boilingpoints, more of the additive is retained during catalyst drying andoptional sulfidation steps, and thus mixtures containing a reasonableproportion of the higher-boiling glycol(s) are preferred. Generally,glycol mixtures in which the molar ratio of tetraethylene glycol and/orpolyethylene glycol to monoethylene glycol, diethylene glycol, and/ortriethylene glycol is about 0.15:1 or more are preferred. Examples ofconvenient ratios for a two-component glycol mixture are 1:1 by weightand 1:1 by moles.

Processes of the invention for forming solution compositions of theinvention comprise bringing together, in an aqueous medium, i) at leastone phosphorus compound; ii) at least one Group VI metal compound; iii)at least one Group VIII metal compound; and iv) an additive which is a)tetraethylene glycol, b) polyethylene glycol having an average molecularweight in the range of about 200 to about 400, c) a mixture oftetraethylene glycol and polyethylene glycol having an average molecularweight in the range of about 200 to about 400, or d) a mixture of (1)tetraethylene glycol and/or polyethylene glycol having an averagemolecular weight in the range of about 200 to about 400 and (2) one ormore of monoethylene glycol, diethylene glycol, and triethylene glycol.The molar ratio of additive to the total moles of Group VI metal andGroup VIII metal is above 0.30:1, based on the amounts of componentsbrought together. Generally, the components are in amounts such that thephosphorus and the Group VI metal are in an atomic ratio of at leastabout 0.33:1, and the Group VI metal and the Group VIII metal areusually in an atomic ratio of at least about 1.5:1.

The Group VI metal is molybdenum, tungsten, and/or chromium; preferablymolybdenum or tungsten, more preferably molybdenum. The Group VIII metalis iron, nickel and/or cobalt, preferably nickel and/or cobalt.Preferred mixtures of metals include a combination of nickel and/orcobalt and molybdenum and/or tungsten. When hydrodesulfurizationactivity of the catalyst is to be emphasized, a combination of cobaltand molybdenum is advantageous and preferred. When hydrodenitrogenationactivity of the catalyst is to be emphasized, a combination of nickeland molybdenum and/or tungsten is advantageous and preferred. Anotherpreferred combination of hydrogenation metals is nickel, cobalt andmolybdenum.

The Group VI metal compound can be an oxide, an oxo acid, or an ammoniumsalt of an oxo or polyoxo anion; these Group VI metal compounds areformally in the +6 oxidation state when the metal is molybdenum ortungsten. Oxides and oxo-acids are preferred Group VI metal compounds.Suitable Group VI metal compounds in the practice of this inventioninclude chromium(III) oxide, ammonium chromate, ammonium dichromate,molybdenum trioxide, molybdic acid, ammonium molybdate, ammoniumpara-molybdate, tungsten trioxide, tungstic acid, ammonium tungstenoxide, ammonium metatungstate hydrate, ammonium para-tungstate, and thelike. Preferred Group VI metal compounds include chromium(III) oxide,molybdenum trioxide, molybdic acid, ammonium para-tungstate, tungstentrioxide and tungstic acid. Mixtures of any two or more Group VI metalcompounds can be used.

The Group VIII metal compound is usually an oxide, hydroxide or a salt.Suitable Group VIII metal compounds include, but are not limited to,iron oxide, iron hydroxide, iron nitrate, iron carbonate, ironhydroxy-carbonate, iron acetate, iron citrate, cobalt oxide, cobalthydroxide, cobalt nitrate, cobalt carbonate, cobalt hydroxy-carbonate,cobalt acetate, cobalt citrate, nickel oxide, nickel hydroxide, nickelnitrate, nickel carbonate, nickel hydroxy-carbonate, nickel acetate, andnickel citrate. Preferred Group VIII metal compounds include ironhydroxide, iron carbonate, iron hydroxy-carbonate, cobalt hydroxide,cobalt carbonate, cobalt hydroxy-carbonate, nickel hydroxide, nickelcarbonate, and nickel hydroxy-carbonate. Mixtures of two or more GroupVIII metal compounds can be used.

In the practice of this invention, the phosphorus compound is typicallya water soluble, acidic phosphorus compound, particularly an oxygenatedinorganic phosphorus-containing acid. Examples of suitable phosphoruscompounds include metaphosphoric acid, pyrophosphoric acid, phosphorousacid, orthophosphoric acid, triphosphoric acid, tetraphosphoric acid,and precursors of acids of phosphorus, such as ammonium hydrogenphosphates. Mixtures of two or more phosphorus compounds can be used.The phosphorus compound may be used in liquid or solid form. A preferredphosphorus compound is orthophosphoric acid (H₃PO₄).

Typically, the concentration of the additive is about 30 g/L to about700 g/L. Preferably, the additive concentration is in the range of about40 g/L to about 680 g/L, and more preferably in the range of about 50g/L to about 650 g/L.

In these processes, an organic acid is optionally included. The optionalorganic acid has at least one acid group and at least one functionalgroup selected from a hydroxyl group and an acid group. Thus, at aminimum, the organic acid has one acid group and one hydroxyl group, ortwo acid groups. As used herein, the term “acid group” means the —COOHmoiety. The organic acid preferably has at least two carboxylic acidmoieties, and preferably has at least about three carbon atoms. It issometimes preferred that the organic acid has at least one hydroxylgroup. Suitable organic acids include citric acid, gluconic acid, lacticacid, malic acid, maleic acid, malonic acid, oxalic acid, tartaric acid,and the like. Citric acid is a preferred organic acid. Mixtures of acidscan be used.

When forming a solution composition of the invention, the Group VI metaland the Group VIII metal are usually in an atomic ratio of at leastabout 1.5:1, preferably in the range of about 1.5:1 to about 6:1, morepreferably in the range of about 2:1 to about 5:1. The atomic ratio ofphosphorus to Group VI metal is typically at least about 0.33:1,preferably in the range of about 0.33:1 to about 0.8:1, more preferablyin the range of about 0.38:1 to about 0.7:1, and still more preferablyabout 0.45:1 to about 0.7:1. Generally, the molar ratio of optionalorganic acid, when present, to the total molar amount of the Group VIand VIII metal components present in the solution is at least about0.01:1, preferably in the range of about 0.01:1 to about 0.6:1, morepreferably in the range of about 01:1 to about 0.4:1. In these relativeamounts, where a mixture of compounds is used, it is understood that thetotal amount of a particular type of compound is used in calculating theratios.

Combining of the components in the process can be done at ambientconditions, i.e., room temperature and ambient pressure. Temperatures inexcess of about 95° C. and/or elevated pressures can be applied (e.g.,hydrothermal preparation), but are not required. When the components arecombined, a primary solution is formed. A recommended method forpreparing the primary solution is via preparation of an initial solutionfrom the phosphorus compound, Group VI metal compound, Group VIII metalcompound, and the additive is then combined with the initial solution toform the primary solution. Usually, the initial solution is heated toensure dissolution of the components.

If the primary solution is not subjected to optional heating or optionalcooling, the primary solution is the solution composition. In theprimary solutions, the concentrations of the Group VI metal (or totalthereof, if more than one Group VI metal is present in the composition)are often in the range of about 1.35 mol/L to about 5.9 mol/L,preferably in the range of about 1.9 mol/L to about 4.2 mol/L. Forprocesses in which solutions having Group VI and Group VIII metalconcentrations at the higher end of this range are formed, when anoptional organic acid is included, it is recommended that at least aportion of the optional organic acid is combined either before orconcurrently with the addition of the Group VIII metal compound.

In the optional heating step, the primary solution is heated at atemperature above about 40° C. to form a heated solution. Elevatedtemperatures can increase the rate of dissolution, and have beenobserved to affect the precipitation properties of solutions formed bythe processes of this invention. More specifically, it has been observedthat digesting (heating) some of the primary solutions which hadprecipitate therein caused the precipitate to dissolve; in thesesolutions, the precipitate did not reform after the solution was cooledto room temperature. Such elevated temperatures for digestion (heating)are typically in the range of about 40° C. to about 95° C., preferablyabout 50° C. to about 95° C., and more preferably about 60° C. to about95° C. This digestion effect was more pronounced for solutions made fromcomponents in which the molar ratio of additive to hydrogenation metalswas higher than about 0.35:1, which solutions had a precipitate beforedigestion, but not after digestion and cooling. Whether to use a lesseramount of additive and digest the solution or to use a greater amount ofadditive such that digestion is not needed is normally a balance of costfor time and energy to heat versus the material cost of using greateramounts of additive.

The heated solution is optionally cooled to form a cooled solution.Often, heated solutions are subjected to the cooling step. Cooling isusually to ambient (room) temperature, typically in the range of about15° C. to about 25° C., often about 17° C. to about 23° C. However, ifthe solution, after preparation, is to be employed at an elevatedtemperature (e.g., 40° C. to 50° C.), the solution only needs to becooled to the temperature at which it will be employed, if thattemperature is lower than the temperature to which the solution washeated during the heating step.

The compositions of the invention, formed in a process as describedabove, are solutions comprising a Group VI metal, a Group VIII metal,phosphorus, and additive which is a) tetraethylene glycol, b)polyethylene glycol having an average molecular weight in the range ofabout 200 to about 400, c) a mixture of tetraethylene glycol andpolyethylene glycol having an average molecular weight in the range ofabout 200 to about 400, or d) a mixture of (1) tetraethylene glycoland/or polyethylene glycol having an average molecular weight in therange of about 200 to about 400 and (2) one or more of monoethyleneglycol, diethylene glycol, and triethylene glycol.

In the compositions of the invention, the mole ratio of the additive tothe total moles of Group VI and Group VIII metals is above 0.30:1. TheGroup VI metal and the Group VIII metal are generally in a molar ratioof at least about 1.5:1 in the compositions of the invention. Thephosphorus and Group VI metal are typically in an atomic ratio of atleast about 0.33:1. Without wishing to be bound by theory, a mixture ofspecies is believed to be present in the solution compositions of thisinvention. At this time, the species in solution are not wellcharacterized. In this connection, for examples of species present insolutions containing molybdenum and phosphorus, see J. Bergwerff, Ph.D.thesis, Utrecht University, The Netherlands, 2007, Chapter 2C.

The solution compositions of this invention generally involve water, andcan be thought of as aqueous solutions, although in at least someinstances the amount of the glycol additive(s) is greater than theamount of water.

In the solutions which are compositions of this invention, the Group VImetal is molybdenum, tungsten, or chromium. Preferably, the Group VImetal is molybdenum or tungsten, more preferably molybdenum. The GroupVIII metal is iron, nickel and/or cobalt, preferably nickel and/orcobalt. The atomic ratios of phosphorus to the Group VI metal in thecomposition are typically at least about 0.33:1, preferably about 0.33:1to about 0.8:1, more preferably about 0.38:1 to about 0.7:1, and stillmore preferably about 0.45:1 to about 0.7:1. The atomic ratio of GroupVI metal to Group VIII metal is generally at least about 1.5:1,preferably in the range of about 1.5:1 to about 6:1, and more preferablyabout 2:1 to about 5:1. The molar ratio of additive to hydrogenationmetals is above about 0.30:1, preferably at least about 0.31:1, morepreferably at least about 0.33:1, and still more preferably at leastabout 0.35:1. Preferably, the molar ratio of additive to hydrogenationmetals is in the range of about 0.30:1 to about 0.6:1, more preferablyin the range of about 0.33:1 to about 0.6:1, still more preferably inthe range of about 0.35:1 to 0.6:1, and especially 0.4:1 to about 0.6:1.

When mixtures of reagents are used in forming the solution compositions,as mentioned above, a mixture of species will be present in thesolution. For example, if a molybdenum compound and a tungsten compoundare used, the product solution will include molybdenum and tungsten. Inanother example, if a cobalt compound and a nickel compound are used,the product solution will include cobalt and nickel. Mixtures ofreagents such that Group VI metal compounds in which the Group VI metalsof the compounds are different and Group VIII metal compounds in whichthe Group VIII metals of the compounds are different can be used informing the solution compositions if desired.

While the concentration of the species in the solution compositions ofthis invention is not of significance for the compositions, it is oftenconvenient to work at concentrations that are practical for furtherintended use of the solution. For example, these solutions can beemployed, as embodied in this invention, to form a catalyst. Suitableconcentrations of the Group VI metal (or total thereof, if more than oneGroup VI metal is present in the composition) in the solutioncompositions of the invention (with the additives present) are typicallyin the range of about 1.35 mol/L to about 5.9 mol/L, preferably in therange of about 1.9 mol/L to about 4.2 mol/L.

Preferred solution concentrations provide catalysts in which the GroupVI metal is present in an amount of about 5 to about 40 wt %, preferablyabout 15 to about 36 wt %, calculated as trioxide; the Group VIII metalis present in an amount of about 1 to about 10 wt %, preferably about 2to about 8 wt %, calculated as monoxide; and phosphorus is present in anamount of about 1 to about 10 wt %, preferably about 2 to about 9 wt %,calculated as P₂O₅.

In processes of the invention for forming catalysts, catalysts areformed by bringing together a carrier and an impregnation solution toform an impregnated carrier, and drying the impregnated carrier to forma catalyst. The impregnation solution comprises a solution compositionof this invention. For impregnation solutions, the preferences for thesolution compositions of the invention are as described above.

Throughout this document, the term “carrier” refers to a carrier whichis in the solid form or is pre-shaped. Such a carrier remainspredominantly in the solid form when contacted with an aqueous medium.The term does not refer to precursor salts, such as sodium aluminate,which dissolve almost completely in an aqueous medium. The carrier maybe composed of conventional oxides, e.g., alumina, silica,silica-alumina, alumina with silica-alumina dispersed therein,alumina-coated silica, silica-coated alumina, magnesia, zirconia, boria,and titania, as well as mixtures of these oxides. Suitable carriers alsoinclude transition aluminas, for example an eta, theta, or gammaalumina. Preferred carriers include of silica, alumina, silica-alumina,alumina with silica-alumina dispersed therein, alumina-coated silica, orsilica-coated alumina, especially alumina or alumina containing up toabout 20 wt % of silica, preferably up to about 12 wt % of silica. Acarrier containing a transition alumina, for example an eta, theta, orgamma alumina is particularly preferred, and a gamma-alumina carrier ismost preferred.

The carrier is normally employed in a conventional manner in the form ofspheres or extrudates. Examples of suitable types of extrudates havebeen disclosed in the literature; see for example U.S. Pat. No.4,028,227. Highly suitable for use are cylindrical particles (which mayor may not be hollow) as well as symmetrical and asymmetrical polylobedparticles (2, 3 or 4 lobes). Shaped carrier particles are typicallycalcined at a temperature in the range of about 400° to about 850° C.

The carrier's pore volume (measured via N₂ adsorption) will generally bein the range of about 0.25 to about 1 mL/g. The specific surface areawill generally be in the range of about 50 to about 400 m²/g (measuredusing the BET method). Generally, the catalyst will have a median porediameter in the range of about 7 nm to about 20 nm, preferably in therange of about 9 nm to about 20 nm, as determined by N₂ adsorption.Preferably, at least about 60% of the total pore volume will be in therange of approximately 2 nm from the median pore diameter. The figuresfor the pore size distribution and the surface area given above aredetermined after calcination of the carrier at about 500° C. for onehour.

Methods for impregnating the carrier are known to the skilled artisan.Preferred methods include co-impregnation. In the processes of thisinvention for forming catalysts, only one impregnation step is needed.In the impregnation step, once the carrier and impregnation solution arebrought together, the mixture is usually homogenized until virtually allof the impregnation solution is taken up into the catalyst. In thistechnique, which is known in the art as pore volume impregnation or asincipient wetness impregnation, the impregnation solution will be takenup virtually completely by the pores of the catalyst, which makes for anefficient use of chemicals, and avoids dust in the product.

There can be a wide number of variations on the impregnation method.Thus, it is possible to apply a plurality of impregnating steps, theimpregnating solutions to be used containing one or more of thecomponent precursors that are to be deposited, or a portion thereof.Instead of impregnating techniques, there can be used dipping methods,spraying methods, and so forth. When carrying out multiple impregnation,dipping, etc., steps, drying and/or calcining may be carried out betweenimpregnation steps. However, a single impregnation step is preferredbecause it is a faster, simpler process, allowing for a higherproduction rate, and is less costly. Single impregnation also tends toprovide catalysts of better quality.

Impregnation of a carrier with a solution composition of the presentinvention yields catalysts in which the Group VIII metal is usuallypresent in an amount of about 1 to about 10 wt %, preferably about 3 toabout 8.5 wt %, calculated as a monoxide. In these catalysts, phosphorusis usually present in an amount of about 1 to about 10 wt %, morepreferably about 2 to about 9 wt %, calculated as P₂O₅. When the GroupVI metal in the catalyst is molybdenum, it will usually be present in anamount of about 35 wt % or less, preferably in an amount of about 15 toabout 35 wt %, calculated as molybdenum trioxide.

After the impregnation step, the impregnated carrier is normally driedto remove the solvent (usually water). The drying step may be carriedout in air, under vacuum, or in the presence of an inert gas. Generally,a drying temperature below about 220° C. is recommended. The impregnatedcarrier (after optional drying, if carried out) is optionally calcinedat a temperature in the range of about 220° to about 650° C., preferablyabout 350° to about 600° C.

Drying of the impregnated carrier is conducted under such conditionsthat at least a portion of the additive remains in the catalyst, i.e.,the additive is not completely removed by evaporation or decomposition.Thus, the drying conditions to be applied depend on the temperature atwhich the additive boils or decomposes; decomposition can includecombustion when the drying is conducted in the presence of oxygen. Inthese processes of the invention, the drying step should be carried outunder such conditions that at least about 50%, preferably at least about70%, more preferably at least about 90%, of the additive which wasincorporated into the catalyst in the impregnation step is still presentin the catalyst after the drying step. It is preferred to keep as muchof the additive as possible in the catalyst during the drying step;however, it is understood that evaporation of some of the additiveduring the drying step cannot always be avoided. A drying temperaturebelow about 220° C. may be necessary; often, a temperature below about120° C. is recommended and preferred.

Optionally, catalysts of the invention may be subjected to a sulfidationstep (treatment) to convert the metal components to their sulfides. Ithas been observed that more of the additive is retained as part of thecatalyst composition during the sufidation step when additives withhigher boiling points are used. In the context of the presentspecification, the phrases “sulfiding step” and “sulfidation step” aremeant to include any process step in which a sulfur-containing compoundis added to the catalyst composition and in which at least a portion ofthe hydrogenation metal components present in the catalyst is convertedinto the sulfidic form, either directly or after an activation treatmentwith hydrogen. Suitable sulfidation processes are known in the art. Thesulfidation step can take place ex situ to the reactor in which thecatalyst is to be used in hydrotreating hydrocarbon feeds, in situ, orin a combination of ex situ and in situ to the reactor.

Ex situ sulfidation processes take place outside the reactor in whichthe catalyst is to be used in hydrotreating hydrocarbon feeds. In such aprocess, the catalyst is contacted with a sulfur compound, e.g., anorganic or inorganic polysulfide or elemental sulfur, outside thereactor and, if necessary, dried. In a second step, the material istreated with hydrogen gas at elevated temperature in the reactor,optionally in the presence of a feed, to activate the catalyst, i.e., tobring the catalyst into the sulfided state.

In situ sulfidation processes take place in the reactor in which thecatalyst is to be used in hydrotreating hydrocarbon feeds. Here, thecatalyst is contacted in the reactor at elevated temperature with ahydrogen gas stream mixed with a sulphiding agent, such as hydrogensulfide or a compound which under the prevailing conditions isdecomposable into hydrogen sulphide. It is also possible to use ahydrogen gas stream combined with a hydrocarbon feed comprising a sulfurcompound which under the prevailing conditions is decomposable intohydrogen sulfide. In the latter case, it is possible to sulfide thecatalyst by contacting it with a hydrocarbon feed comprising an addedsulfiding agent such as dimethyldisulfide (spiked hydrocarbon feed), andit is also possible to use a sulfur-containing hydrocarbon feed withoutany added sulfiding agent, since the sulfur components present in thefeed will be converted into hydrogen sulfide in the presence of thecatalyst. Combinations of the various sulfiding techniques may also beapplied. The use of a spiked hydrocarbon feed may be preferred.

The catalyst compositions of this invention are those produced by theabove-described process, whether or not the process included an optionalsulfiding step.

The catalyst compositions of this invention can be used in thehydrotreating, hydrodenitrogenation, and/or hydrodesulfurization of awide range of hydrocarbon feeds. Examples of suitable feeds includemiddle distillates, kero, naphtha, vacuum gas oils, heavy gas oils, andthe like.

Methods of the invention are methods for hydrotreating,hydrodenitrogenation, and/or hydrodesulfurization of a hydrocarbon feed,which methods comprise contacting a hydrocarbon feed and a catalyst ofthe invention. Hydrotreating of hydrocarbon feeds involves treating thefeed with hydrogen in the presence of a catalyst composition of theinvention at hydrotreating conditions.

Conventional hydrotreating process conditions, such as temperatures inthe range of about 250° to about 450° C., reactor inlet hydrogen partialpressures in the range of about 5 to about 250 bar, space velocities inthe range of about 0.1 to about 10 vol./vol.hr, and H₂/feed ratios inthe range of about 50 to about 2000 NL/L, can be applied.

The following examples are presented for purposes of illustration, andare not intended to impose limitations on the scope of this invention.

Example 1

In a flask, a solution was prepared by dispersing NiCO₃ powder (98.7 g;49 wt % Ni) in water to make a stirrable slurry. H₃PO₄ (aq., 85%, 174.9g) was then added to the slurry, followed by MoO₃ (369.2 g). The slurrywas then heated at 92° C. until the slurry became a clear solutionhaving 41.9 wt % MoO₃. This was solution A, in which the P:Mo molarratio was 0.58:1.

Eleven 15 mL flasks were each filled with 8.8 g of solution A.Polyethylene glycol-200 in varying amounts was added to each flask; theamounts are listed in Table 1 below. One flask had no polyethyleneglycol-200 added, and is a comparative run. Water was added to eachflask to obtain a final volume of 9.27 mL. Each flask was shaken and theamount of precipitate (height of solid in the flask, in mm) was recordedafter one day. The flasks were then placed in a 60° C. oven for one day,after which the amount of precipitate was again recorded. The flaskswere then removed from the oven and were allowed to cool to roomtemperature. After another day, the amount of precipitate in each flaskwas recorded again. Results are summarized in Table 1; runs 1-6 arecomparative.

TABLE 1 Mol. ratio Amt. PEG- addi- Before Cooled to Run 200¹tive:metals² heating At 60° C. room T 1 0 g   0:1 No precip. No precipNo precip. 2 0.395 g 0.06:1 Precip. - 1 mm No precip Precip. - 2.1 mm 30.79 g 0.12:1 Precip. - 3 mm No precip Precip. - 3.0 mm 4 1.185 g 0.18:1Precip. - 3 mm No precip Precip. - 1.2 mm 5 1.58 g 0.24:1 Precip. - 2 mmNo precip. Precip. - 1.5 mm 6 1.975 g  0.3:1 Precip. - 1 mm No precip.Precip. - 0.6 mm 7 2.37 g 0.36:1 Precip. - 0.3 mm No precip. No precip.8 2.765 g 0.42:1 No precip. No precip. No precip. 9 3.16 g 0.48:1 Noprecip. No precip. No precip. 10 3.555 g 0.54:1 No precip. No precip. Noprecip. 11 3.95 g  0.6:1 No precip. No precip. No precip. ¹Polyethyleneglycol-200. ²Here, the term “metals” refers to hydrogenation metals.

Example 2

In a flask, a solution was prepared by dispersing NiCO₃ powder (73.0 g;49 wt % Ni) in water to make a stirrable slurry. H₃PO₄ (aq., 85%, 31.43g) was then added to the slurry, followed by MoO₃ (273.12 g). The slurrywas then heated at 92° C. until the slurry became a clear solutionhaving 46.4 wt % MoO₃. This was solution B, in which the P:Mo molarratio was 014:1. In all of the inventive runs of this Example, moreH₃PO₄ was added as described herein.

Eight 30 mL flasks (experiments a to h) were each filled with differentamounts of solution A or B (see Table 2 below). To some of the flasks,additional H₃PO₄ (aq., 85 wt %) was added; the amounts are listed inTable 2 below. The additional H₃PO₄ was mixed into the respectivesolutions. Then 0.22 mol of polyethylene glycol-200/(mol Mo+Ni) wasadded to each flask (for amount see Table 2). After mixing thepolyethylene glycol-200 into the solution, water was added to each flaskto obtain a final volume of 19.25 mL. Each flask was shaken again andthe presence of precipitate was recorded after one day. The flasks werethen placed in a 60° C. oven for one day, after which the presence ofprecipitate was recorded again. The results are summarized in Table 2;runs a-d are comparative.

TABLE 2 Amt. Additional Amt. PEG- H₃PO₄ Molar ratio Before Run Soln.Soln. 200^(1,2) (85%) P:Mo heating At 60° C. a B 18.39 g 3.35 g  0.00 g³0.14:1 No precip. No precip. b B  18.6 g 3.39 g 0.47 g 0.21:1 Precip. Noprecip. c B 18.74 g 3.41 g 0.77 g 0.25:1 Precip. No precip. d B 18.87 g3.44 g 1.07 g 0.29:1 Precip. No precip. e B 19.01 g 3.46 g 1.37 g 0.33:1Precip. No precip. f B 19.15 g 3.49 g 1.68 g 0.37:1 Precip. Precip. g B 19.3 g 3.51 g 2.00 g 0.41:1 Precip. Precip. h A   22 g 3.63 g  0.00 g⁴0.58:1 Precip. Precip. ¹Polyethylene glycol-200. ²The molar ratio ofadditive:metals in all runs was 0.22:1; the term “metals” refers tohydrogenation metals. ³All of the H₃PO₄ is from Solution B. ⁴All of theH₃PO₄ is from Solution A.

Example 3

The experiments as described in Example 2 were repeated, but with 0.44mol polyethylene glycol-200/(mol Mo+Ni). These experiments (i to p) aresummarized in Table 3 below; experiments i-l are comparative.

TABLE 3 Additional Molar Amt. Amt. H₃PO₄ ratio Room Run Soln. Soln.PEG-200^(1,2) (85%) P:Mo temp. i B 18.39 g  6.7 g  0.00 g³ 0.14:1 Noprecip. j B  18.6 g 6.78 g 0.47 g 0.21:1 No precip. k B 18.74 g 6.82 g0.77 g 0.25:1 No precip. l B 18.87 g 6.88 g 1.07 g 0.29:1 No precip. m B19.01 g 6.92 g 1.37 g 0.33:1 No precip. n B 19.15 g 6.98 g 1.68 g 0.37:1No precip. o B  19.3 g 7.02 g 2.00 g 0.41:1 No precip. p A   22 g 7.26 g 0.00 g⁴ 0.58:1 Precip. ¹Polyethylene glycol-200. ²The molar ratio ofadditive:metals in all runs was 0.44:1; the term “metals” refers tohydrogenation metals. ³All of the H₃PO₄ is from Solution B. ⁴All of theH₃PO₄ is from Solution A.

The results in Tables 2 and 3 show that with 0.22 mol polyethyleneglycol-200/(mol Mo+Ni), precipitate formation starts at a P:Mo molarratio of about 0.21:1 at room temperature. At 60° C., precipitateformation starts at about a P:Mo molar ratio of about 0.37:1. With thedoubled amount of polyethylene glycol-200 in Example 3, precipitateformation at room temperature starts at a P:Mo molar ratio of about0.58:1.

Example 4

In a flask, a solution was prepared by dispersing NiCO₃ powder (40.26 g;48.8 wt % Ni) in water to make a stirrable slurry. About 30% of theH₃PO₄ (aq., 85%, total amount 71.1 g) was then added to the slurry,followed by MoO₃ (100% MoO₃; 150 g). The slurry was then heated at 92°C. for about 30 minutes, after which the remaining H₃PO₄ was added. Theheating was continued until a clear solution containing 828 g MoO₃/L(˜5.75 mol MoO₃/L) was obtained. The final volume of the solution wasca. 181 mL. This was solution C, in which the P:Mo molar ratio was0.6:1.

Six 15 mL flasks were each filled with 12.0 g of solution C.Polyethylene glycol-300 in varying amounts was added to each flask; theamounts are listed in Table 4 below. One flask had no polyethyleneglycol-300 added, and is a comparative run. Water was added to eachflask to obtain a final volume of 10 mL. Each flask was shaken andchecked for the presence of precipitate after one day. The flasks werethen placed in a 60° C. oven for one day and then they were againchecked for the presence of precipitate. The flasks were then removedfrom the oven and were allowed to cool to room temperature. Afteranother day, the flasks were again checked for the presence ofprecipitate. Results are summarized in Table 4; runs 1-5 arecomparative.

TABLE 4 Mol. ratio Amt. PEG- addi- Before Cooled to Run 300¹tive:metals² heating At 60° C. room T 1   0 g  0:1 No precip. No precip.No precip. 2 1.41 g 0.1:1 Precip. — — 3 2.77 g 0.2:1 Precip. — — 4 3.47g 0.25:1  Precip. Precip. Precip. 5 4.44 g 0.32:1  Precip. Precip.Precip. 6  5.49 g³ 0.4:1 No precip. — — ¹Polyethylene glycol-300. ²Here,the term “metals” refers to hydrogenation metals. ³Final volume was 10.9mL.

Example 5

Seven 15 mL flasks were each filled with 12.0 g of solution C (preparedas described in Example 4). Polyethylene glycol-400 in varying amountswas added to each flask; the amounts are listed in Table 5 below. Oneflask had no polyethylene glycol-400 added, and is a comparative run.Water was added to each flask to obtain a final volume of 10 mL. Eachflask was shaken and checked for the presence of precipitate after oneday. The flasks were then placed in a 60° C. oven for one day and thenthey were again checked for the presence of precipitate. The flasks werethen removed from the oven and were allowed to cool to room temperature.After another day, the flasks were again checked for the presence ofprecipitate. Results are summarized in Table 5; runs 1-6 arecomparative.

TABLE 5 Mol. ratio Amt. PEG- addi- Before Cooled to Run 400¹tive:metals² heating At 60° C. room T 1   0 g   0:1 No precip. No precipNo precip. 2 1.84 g  0.1:1 Precip. — — 3 2.75 g 0.15:1 Precip. — — 43.67 g 0.20:1 Precip. — — 5 4.45 g 0.24:1 Precip. Precip. Precip. 6 5.49 g³ 0.30:1 Precip. — — 7  8.30 g⁴ 0.45:1 Trace precip. — —¹Polyethylene glycol-400. ²Here, the term “metals” refers tohydrogenation metals. ³Final volume was 10.9 mL. ⁴Final volume was 13.4mL.

Example 6

Five 15 mL flasks were each filled with 12.0 g of solution C (preparedas described in Example 4). A 50:50 (weight basis) mixture ofpolyethylene glycol-300 and triethylene glycol (TEG) was added to eachflask in varying amounts; the amounts are listed in Table 6 below. Oneflask had no polyethylene glycol-300 and triethylene glycol (TEG) added,and is a comparative run. Water was added to each flask to obtain afinal volume of 10 mL. Each flask was shaken and checked for thepresence of precipitate after one day. The flasks were then placed in a60° C. oven for one day and then they were again checked for thepresence of precipitate. The flasks were then removed from the oven andwere allowed to cool to room temperature. After another day, the flaskswere again checked for the presence of precipitate. Results aresummarized in Table 6; runs 1-3 are comparative.

TABLE 6 Amt. Amt. Mol. ratio Before Cooled to Run PEG-300¹ TEG²additive³:metals⁴ heating At 60° C. room T 1   0 g   0 g   0:1 Noprecip. No precip No precip. 2 1.26 g 1.26 g 0.27:1 Precip. Precip.Precip. 3 1.38 g 1.38 g 0.30:1 Precip. Precip. Precip. 4 1.91 g 1.91 g0.41:1 Precip. No precip. No precip. 5 2.25 g 2.25 g 0.49:1 Precip. Noprecip. No precip. ¹Polyethylene glycol-300. ²Triethylene glycol (TEG).³Mol. additive = mol. polyethylene glycol-300 + mol. triethylene glycol(TEG). ⁴Here, the term “metals” refers to hydrogenation metals.

Example 7

Five 15 mL flasks were each filled with 12.0 g of solution C (preparedas described in Example 4). A 50:50 (weight basis) mixture ofpolyethylene glycol-400 and triethylene glycol (TEG) was added to eachflask in varying amounts; the amounts are listed in Table 7 below. Oneflask had no polyethylene glycol-400 and triethylene glycol (TEG) added,and is a comparative run. Water was added to each flask to obtain afinal volume of 10 mL. Each flask was shaken and checked for thepresence of precipitate after one day. The flasks were then placed in a60° C. oven for one day and then they were again checked for thepresence of precipitate. The flasks were then removed from the oven andwere allowed to cool to room temperature. After another day, the flaskswere again checked for the presence of precipitate. Results aresummarized in Table 7; runs 1-4 are comparative.

TABLE 7 Amt. Cooled PEG- Amt. Mol. ratio Before At to Run 400¹ TEG²additive³:metals⁴ heating 60° C. room T 1   0 g   0 g   0:1 No No Noprecip. precip precip. 2 0.74 g 0.74 g 0.15:1 Precip. Precip. Precip. 31.24 g 1.24 g 0.25:1 Precip. Precip. Precip. 4 1.76 g 1.76 g 0.35:1Precip. Precip. Precip. 5 2.24 g 2.24 g 0.45:1 Precip. Precip. Noprecip. ¹Polyethylene glycol-400. ²Triethylene glycol (TEG). ³Mol.additive = mol. polyethylene glycol-400 + mol. triethylene glycol (TEG).⁴Here, the term “metals” refers to hydrogenation metals.

Example 8 (Comparative)

Five 15 mL flasks were each filled with 12.0 g of solution C (preparedas described in Example 4). Polyethylene glycol-600 in varying amountswas added to each flask; the amounts are listed in Table 8 below. Oneflask had no polyethylene glycol-600, and is a comparative run. Waterwas added to each flask to obtain a final volume of 10 mL. Each flaskwas shaken and checked for the presence of precipitate after one day.The flasks were then placed in a 60° C. oven for one day and then theywere again checked for the presence of precipitate. The flasks were thenremoved from the oven and were allowed to cool to room temperature.After another day, the flasks were again checked for the presence ofprecipitate. Results are summarized in Table 8.

TABLE 8 Mol. ratio Amt. PEG- addi- Before Cooled to Run 600¹tive:metals² heating At 60° C. room T 1   0 g   0:1 No precip. No precipNo precip. 2 1.38 g 0.05:1 Precip. Precip. Precip. 3 2.75 g 0.10:1Precip. Precip. Precip. 4 4.21 g 0.15:1 Precip. Precip. Precip. 5 4.48 g0.16:1 Precip. Precip. Precip. ¹Polyethylene glycol-600. ²Here, the term“metals” refers to hydrogenation metals.

Example 9

In a flask, a solution was prepared by adding just enough water to NiCO₃powder (49 wt % Ni in NiCO₃, 90.93 g) to make a stirrable suspension.H₃PO₄ (aq., 85%, 39.12 g) was then added to the suspension, followed byabout 40% of the MoO₃ (total amount of MoO₃: 340 g). The suspension wasthen heated at 92° C. until the suspension became more stirrable, thenthe remaining MoO₃ was added stepwise. After about 30 minutes at 92° C.,a clear solution was obtained. The final volume of this solution was ca.400 mL. The concentrations of the resulting solution were 850 g MoO₃/L(˜5.90 mol Mo/L), 142 g NiO/L (˜1.89 mol Ni/L), and 60.2 g P₂O₅/L (˜0.85mol P/L). This was solution D, in which the P:Mo molar ratio was 0.14:1.In all of the inventive runs of this Example, more H₃PO₄ was added asdescribed herein; after adding the further H₃PO₄, the P:Mo molar ratiowas 0.55:1 in all runs.

Six 15 mL flasks were each filled with 3.04 mL of solution D. Thesolution composition was varied by the addition of water, followed bythe addition of citric acid (50 wt. % solution; 1.319 g/ml), followed bythe addition of H₃PO₄ (85 wt. %; 1.71 g/mL) and, finally, polyethyleneglycol-200 (PEG-200, 100 wt. %; 1.128 g/mL) was added to the solution.Water was added to each flask to obtain a final volume of 7 mL. Theamounts of H₃PO₄, polyethylene glycol-200, and citric acid added arelisted in Table 9. Each flask was shaken and checked for the presence ofprecipitate after one day; all flasks contained precipitate. The flaskswere then placed in a 60° C. oven for one day, removed from the oven,and allowed to cool to room temperature. After another day, the flaskswere again checked for the presence of precipitate, and the amount ofprecipitate (height of solid in the flask, in mm) was recorded. Resultsare summarized in Table 9; runs 1-4 are comparative.

TABLE 9 Amt. Amt. Mol. ratio Amt. Before After heating and Run H₃PO₄ ¹PEG-200² additive:metals³ citric acid heating cooling to room T 1 0.49mL 0.56 mL 0.14:1 0 Precip. Precip. - 8 mm 2 0.49 mL 0.56 mL 0.14:1 1.04mL Precip. Precip. - 13 mm 3 0.49 mL 1.12 mL 0.28:1 0 Precip. Precip. -10 mm 4 0.49 mL 1.12 mL 0.28:1 1.04 mL Precip. Precip. - 13 mm 5 0.49 mL2.24 mL 0.55:1 0 Precip. No precip. 6 0.49 mL 2.24 mL 0.55:1 1.04 mLPrecip. No precip. ¹In addition to that present from solution D.²Polyethylene glycol-200. ³Here, the term “metals” refers tohydrogenation metals.

Components referred to by chemical name or formula anywhere in thespecification or claims hereof, whether referred to in the singular orplural, are identified as they exist prior to coming into contact withanother substance referred to by chemical name or chemical type (e.g.,another component, a solvent, or etc.). It matters not what chemicalchanges, transformations and/or reactions, if any, take place in theresulting mixture or solution as such changes, transformations, and/orreactions are the natural result of bringing the specified componentstogether under the conditions called for pursuant to this disclosure.Thus the components are identified as ingredients to be brought togetherin connection with performing a desired operation or in forming adesired composition.

The invention may comprise, consist, or consist essentially of thematerials and/or procedures recited herein.

As used herein, the term “about” modifying the quantity of an ingredientin the compositions of the invention or employed in the methods of theinvention refers to variation in the numerical quantity that can occur,for example, through typical measuring and liquid handling proceduresused for making concentrates or use solutions in the real world; throughinadvertent error in these procedures; through differences in themanufacture, source, or purity of the ingredients employed to make thecompositions or carry out the methods; and the like. The term about alsoencompasses amounts that differ due to different equilibrium conditionsfor a composition resulting from a particular initial mixture. Whetheror not modified by the term “about”, the claims include equivalents tothe quantities.

Except as may be expressly otherwise indicated, the article “a” or “an”if and as used herein is not intended to limit, and should not beconstrued as limiting, the description or a claim to a single element towhich the article refers. Rather, the article “a” or “an” if and as usedherein is intended to cover one or more such elements, unless the textexpressly indicates otherwise.

This invention is susceptible to considerable variation in its practice.Therefore the foregoing description is not intended to limit, and shouldnot be construed as limiting, the invention to the particularexemplifications presented hereinabove.

That which is claimed is:
 1. A method for hydrotreating,hydrodenitrogenation, and/or hydrodesulfurization, which methodcomprises I) forming an impregnation solution, by A) bringing together,in an aqueous medium, i) at least one phosphorus compound, ii) at leastone Group VI metal compound, iii) at least one Group VIII metalcompound, and iv) an additive which is a) tetraethylene glycol, b)polyethylene glycol having an average molecular weight in the range ofabout 200 to about 400, c) a mixture of tetraethylene glycol andpolyethylene glycol having an average molecular weight in the range ofabout 200 to about 400, or d) a mixture of (1) tetraethylene glycoland/or polyethylene glycol having an average molecular weight in therange of about 200 to about 400 and (2) one or more of monoethyleneglycol, diethylene glycol, and triethylene glycol, where the molar ratioof additive to the total moles of Group VI metal and Group VIII metal isabout 0.36:1 to about 0.6:1, and where the atomic ratio of phosphorus toGroup VI metal is at least about 0.33:1, to form a solution, B)optionally heating said solution at a temperature above about 40° C.;and C) optionally cooling said solution, wherein the solution has aconcentration of Group VI metal of about 1.35 mol/L to about 3.3 mol/L;and II) bringing together a carrier and the impregnation solution toform an impregnated carrier; and III) drying the impregnated carrier,and IV) optionally calcining the impregnated carrier, to form acatalyst, optionally sulfiding the catalyst, and contacting ahydrocarbon feed and the catalyst.
 2. A method as in claim 1 wherein theGroup VI metal is molybdenum, and wherein the molybdenum is present inthe catalyst in an amount of about 5 to about 40 wt %, calculated asmolybdenum trioxide.
 3. A method as in claim 1 wherein said atomic ratioof phosphorus to Group VI metal is about 0.33:1 to about 0.8:1, and/orwherein said Group VI metal compound and the Group VIII metal compoundare in an amount such that the Group VI metal and the Group VIII metalare in an atomic ratio of at least about 1.5:1.
 4. A method as in claim1 wherein said phosphorus compound is a water soluble, acidic phosphoruscompound.
 5. A method as in claim 4 wherein said phosphorus compound isorthophosphoric acid.
 6. A method as in claim 1 wherein said Group VIIImetal compound is a carbonate, hydroxide, or hydroxy-carbonate, and/orwherein said Group VI metal compound is an oxide or an oxo-acid.
 7. Amethod as in claim 1 wherein said additive is polyethylene glycol havingan average molecular weight in the range of about 200 to about 400, or amixture of triethylene glycol and tetraethylene glycol and/orpolyethylene glycol having an average molecular weight in the range ofabout 200 to about
 400. 8. A method as in claim 1 wherein an organicacid is present in the impregnation solution, which organic acid has atleast one acid group and at least one functional group selected from ahydroxyl group and an acid group.
 9. A method as in claim 8 wherein saidorganic acid is citric acid.
 10. A method as in claim 1 wherein saidGroup VI metal is molybdenum and/or tungsten, and/or wherein said GroupVIII compound is a nickel or cobalt compound.
 11. A method as in claim 1wherein I) comprises a single impregnation step.
 12. A method as inclaim 1 wherein said carrier is silica, alumina, silica-alumina, aluminawith silica-alumina dispersed therein, alumina-coated silica, orsilica-coated alumina.
 13. A method as in claim 1 wherein at least oneorganic acid, which organic acid has at least one acid group and atleast one functional group selected from a hydroxyl group and an acidgroup, is present in the impregnation solution.
 14. A method as in claim13 wherein said organic acid is citric acid.
 15. A method as in claim 1wherein the molar ratio of additive to the total moles of Group VI metaland Group VIII metal is in the range of 0.4:1 to 0.6:1, and/or whereinthe atomic ratio of phosphorus to Group VI metal is in the range of0.38:1 to 0.7:1.
 16. A method as in claim 15 wherein the carrier is anoxide, wherein the Group VI metal is molybdenum, and/or wherein theadditive is polyethylene glycol having an average molecular weight ofabout 200 or about
 300. 17. A method as in claim 1 wherein the carrieris an oxide, wherein the Group VI metal is molybdenum, and/or whereinthe additive is polyethylene glycol having an average molecular weightof about 200 or about 300.